Buggy code:
public class FileFilterTestCase extends FileBasedTestCase { static final String SVN_DIR_NAME = ".svn" ; private static final boolean WINDOWS = ( File . separatorChar ) == '\\' ; public FileFilterTestCase ( String name ) { } @ Override public void setUp ( ) { } @ Override public void tearDown ( ) throws Exception { } public void assertFiltering ( IOFileFilter filter , File file , boolean expected ) throws Exception { } public void testSuffix ( ) throws Exception { IOFileFilter filter = new SuffixFileFilter ( new String [ ] { "tes" , "est" } ) ; File testFile = new File ( "test" ) ; File fredFile = new File ( "fred" ) ; assertFiltering ( filter , new File ( "fred.tes" ) , true ) ; assertFiltering ( filter , new File ( "fred.est" ) , true ) ; assertFiltering ( filter , new File ( "fred.EST" ) , false ) ; assertFiltering ( filter , new File ( "fred.exe" ) , false ) ; <START_BUG> filter = FileFilterUtils . orFileFilter ( FileFilterUtils . suffixFileFilter ( "tes" ) , FileFilterUtils . suffixFileFilter ( "est" ) ) ; <END_BUG> assertFiltering ( filter , new File ( "fred" ) , false ) ; assertFiltering ( filter , new File ( ".tes" ) , true ) ; assertFiltering ( filter , new File ( "fred.test" ) , true ) ; filter = new SuffixFileFilter ( "est" ) ; assertFiltering ( filter , new File ( "test" ) , true ) ; assertFiltering ( filter , new File ( "fred" ) , false ) ; assertTrue ( filter . accept ( testFile . getParentFile ( ) , testFile . getName ( ) ) ) ; assertTrue ( ( ! ( filter . accept ( fredFile . getParentFile ( ) , fredFile . getName ( ) ) ) ) ) ; List < String > prefixes = Arrays . asList ( new String [ ] { "ood" , "red" } ) ; IOFileFilter listFilter = new SuffixFileFilter ( prefixes ) ; assertTrue ( ( ! ( listFilter . accept ( testFile . getParentFile ( ) , testFile . getName ( ) ) ) ) ) ; assertTrue ( listFilter . accept ( fredFile . getParentFile ( ) , fredFile . getName ( ) ) ) ; try { new SuffixFileFilter ( ( ( String ) ( null ) ) ) ; fail ( ) ; } catch ( IllegalArgumentException ex ) { } try { new SuffixFileFilter ( ( ( String [ ] ) ( null ) ) ) ; fail ( ) ; } catch ( IllegalArgumentException ex ) { } try { new SuffixFileFilter ( ( ( List < String > ) ( null ) ) ) ; fail ( ) ; } catch ( IllegalArgumentException ex ) { } } public void testSuffixCaseInsensitive ( ) throws Exception { } public void testDirectory ( ) throws Exception { } public void testFiles ( ) throws Exception { } public void testPrefix ( ) throws Exception { } public void testPrefixCaseInsensitive ( ) throws Exception { } public void testNameFilter ( ) throws Exception { } public void testNameFilterNullArgument ( ) throws Exception { } public void testNameFilterNullArrayArgument ( ) throws Exception { } public void testNameFilterNullListArgument ( ) throws Exception { } public void testTrue ( ) throws Exception { } public void testFalse ( ) throws Exception { } public void testNot ( ) throws Exception { } public void testAnd ( ) throws Exception { } public void testOr ( ) throws Exception { } public void testFileFilterUtils_and ( ) throws Exception { } public void testFileFilterUtils_or ( ) throws Exception { } @ SuppressWarnings ( "deprecation" ) public void testDeprecatedWildcard ( ) throws Exception { } public void testWildcard ( ) throws Exception { } public void testDelegateFileFilter ( ) throws Exception { } public void testMakeCVSAware ( ) throws Exception { } public void testMakeSVNAware ( ) throws Exception { } public void testAgeFilter ( ) throws Exception { } public void testSizeFilter ( ) throws Exception { } public void testHidden ( ) throws Exception { } public void testCanRead ( ) throws Exception { } public void testCanWrite ( ) throws Exception { } public void testEmpty ( ) throws Exception { } public void testMakeDirectoryOnly ( ) throws Exception { } public void testMakeFileOnly ( ) throws Exception { } public void testMagicNumberFileFilterBytes ( ) throws Exception { } public void testMagicNumberFileFilterBytesOffset ( ) throws Exception { } public void testMagicNumberFileFilterString ( ) throws Exception { } public void testMagicNumberFileFilterStringOffset ( ) throws Exception { } public void testFilterArray ( ) throws Exception { } public void testFilterArray_fromList ( ) throws Exception { } public void testFilterArrayNullParameters ( ) throws Exception { } public void testFilterList ( ) throws Exception { } public void testFilterList_fromArray ( ) throws Exception { } public void testFilterListNullParameters ( ) { } public void testFilterSet ( ) throws Exception { } public void testFilterSet_fromArray ( ) throws Exception { } public void testFilterSetNullParameters ( ) { } }

Fix:
filter = FileFilterUtils . or ( FileFilterUtils . suffixFileFilter ( "tes" ) , FileFilterUtils . suffixFileFilter ( "est" ) ) ;